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AssigneeThe Toyo Rubber Industry Co., Ltd.
InventorsTakuya Okazaki, Toyohiko Asada, Masahide Nishihata, Yukitoshi Morishita, Keijiro Oda
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A pneumatic radial-ply tire having a tread constructed of at least two kinds of rubber which is capable of attaining both braking performance and rolling resistance. The tread portion is constructed so that the tread center zone is comprised of a rubber having a low hysteresis loss and the tread side zones adjacent to the center zone on both sides thereof or the outer layers of them are each comprised of a rubber having a high hysteresis loss; the tread center zone and the tread side zones are disposed in parallel to each other in the circumferential direction or the tread side zones are each disposed adjoining to the tread center zone and in a superposing manner.
A pneumatic radial-ply tire having a tread portion constructed of at least two kinds of rubber, said tire comprising carcass plies fastened to a pair of bead cores at both edges thereof and belt plies and a tread portion disposed in the area outside the carcass, in which said tread portion is constructed so that a tread center zone is composed of a rubber having a low hysteresis loss factor (tan .delta.), as measured on a dynamic viscoelastomer under the conditions of 60.degree. C. and 11 Hz, of not more than 0.15 and tread size zones extending on both sides of the tread center zone which are each composed of a rubber having a high hystersis loss factor (tan .delta.) of more than 0.15 as measured on a dynamic viscoelastometer under the conditions of 60.degree. C. and 11 Hz;
A pneumatic radial-ply tire having a tread portion constructed of at least two kinds of rubber, said tire comprising carcass plies fastened to a pair of bead cores at both edges thereof and belt plies and a tread portion disposed in the area outside the carcass, in which said tread portion is constructed so that a tread center zone is composed of a rubber having a low hysteresis loss factor (tan .delta.), as measured on a dynamic viscoelastometer under the conditions of 60.degree. C. and 11 Hz, of not more than 0.15 and tread side zones extending on both sides of the tread center zone which are each composed of a rubber having a high hysteresis loss factor (tan .delta.) of more than 0.15 measured on a dynamic viscoelastometer under the conditions of 60.degree. C. and 11 Hz;
Dependencies are inferred from the claim text.